The Level of HIV infection among black people is about 1,000 times that of whites, which is why the row over "white" and "black" blood for transfusions is a medical and not a political issue.

This is the view of outspoken independent forensic scientist Dr David Klatzow, who was commenting on the furore that has erupted after it emerged that the South African National Blood Transfusion Service had destroyed some of the blood donated by black and coloured people.

Among those who have condemned the blood transfusion service's practice are Health Minister Manto Tshabalala-Msimang and the Human Rights Commission.

Jody Kollapen, the commission's chairperson, said: "The commission supports all efforts to ensure a safe blood supply, but we don't support the broad exclusion of people based on the criteria of race. The organisation's practices not only violate the equality commitment we have as South Africans but also impacts on the dignity of millions of black people who want to perform their civic duty."

But Klatzow says the issue has nothing to do with racial stereotyping.

"The issue is purely one of risk management it has entirely to do with providing the safest possible blood products for everybody in this country, irrespective of race."

He said the blood transfusion service had tested the blood of every donor since the 1980s to establish the true prevalence of HIV infections in the different blood-donating cohorts or groups.

"The undeniable statistics show that some of those cohorts have a vastly increased level of HIV infection, and when I say vastly I mean in order of a thousand times. That is to say the level of HIV infection in the black group is approximately 1 000 times greater than that in the white corresponding group.

"It is a tragedy that the Aids incidence follows the socio-economic inequalities of the past, but to deny that in the approach to safe blood is to take one tragedy and convert it into a second tragedy - with the additional element of farce thrown in."

Klatzow pointed out that just three years ago the head of the French blood transfusion service had been prosecuted for culpable homicide in the criminal courts for failing to take all the necessary steps to prevent the transmission of HIV.

"It is utterly intolerable that Professor Anthon Heyns and Dr Robert Crooks of the South African National Blood Transfusion Service, and the other experts in this field, should be subjected to the political whims of people who in the past have shown themselves to be ignorami in the question of Aids and Aids policy.

"All the garlic and African potatoes that Tshabalala-Msimang can provide won't alter that fact. The only thing that will alter it is to make the high risk group aware of the problems and to change their behaviour, and this is not going to be done by political posturing."

"I think that before they consider racial profiling as a means to determine risk, they should make sure they have a screening process which is equal and accurate in place," she said.

Kadalie was also concerned about whether there would be enough blood available with the festive season approaching if black people were not considered eligible donors.

Dr Arthur Bird, the medical director at the Western Province Blood Transfusion Service, said they had been relying on the standard risk management process for a few years and had never felt the need to use race to assess blood risk levels.

Bird described the current furore as "a difficult issue".

"I think any situation where race is used as a marker can become emotive considering our country's history" he said.

President Thabo Mbeki's blood, which he donated in Durban in 2001, was incinerated after he failed to complete a mandatory questionnaire.